Results of thermal stratification tests in a horizontal pipe line at the HDR-facility

Global and local stresses of the pipe wall have been analyzed based on the HDR thermal stratification experiments, existing of the simulation of typical feedwater stratification phenomena in both pressurized and boiling water reactors. The measured global stresses due to the wall temperature differences have been compared to analytical values. The effect of support conditions of the piping has been clarified by an example. The highly transient local stresses due to the temperature fluctuations in the mixing layer have been evaluated on the basis of measured inside wall surface temperatures. The measured fluid and wall temperature fluctuations have been compared. Also the effect of stress fluctuations on fatigue has been estimated. (orig.)